Prior art structures related to apparatus for controlling the venting of a fuel tank or fuel conduit or for controlling evaporation of fuel are shown in the U.S. Shaw Pat. No. 2,145,739, issued Jan. 31, 1939; the U.S. Tirloni Pat. No. 2,964,029, issued Dec. 13, 1960; the U.S. Cornelius Pat. No. 3,640,257, issued Feb. 8, 1972, and the U.S. Hunter Pat. No. 3,687,335, issued Aug. 29, 1972.
Attention is also directed to the U.S. Robert Pat. No. 4,028,075, issued June 7, 1977; Italian Pat. No. 702,125; British Pat. No. 1,431,161; German Offenlegungsschrift No. 2,406,843 issued July 1974; and Japanese Pat. No. 55-19907.